[Exim] Applying embedded perl to specific addresses.

Hi,

I've read through the archives, and the online documentation, but
the information regarding embedded perl in Exim is very brief.

I have compiled exim to include perl support, and developed a perl
script to use in order to parse incoming email to specific
addresses, and grep information out of the local body for use in a
dynamically created email.
(http://dev.detritus.co.uk/perl/exim.pl.txt if anyone even cares.
;) )

I can't see any information as to the most efficient method to do
this. (Router, Director, filter, etc.)

Before I try each method to see which is best, I thought I'd ask if
anyone has done this already and what the recommended method would
be.

Thanks for any advice.

-- 
  ~~ \\\\        Barry R.
~~~  \\\\\__o 
 ~~  \\\\\'/  
______OOOO_____  Even Hedgehogs like skating...